Flexible drawback assembly for package tying machine

ABSTRACT

A flexible drawback assembly for use in a package tying machine, the assembly being connected to the twine wrapper arm of the tying machine for rotation therewith, and including a connector stem, resilient flexor means, and an extended drawback lever terminating in a string-guide eyelet. The flexible drawback assembly is resiliently operable and laterally deflectible to maintain a desired running tension on the twine while simultaneously taking up excess slack, and further provides extended take-up capabilities since it is relatively unaffected by centrifugal forces, quickly reacts to twine slack variations, and inherently limits its own range of travel in relation to the wrapper arm.

United States Patent [1 1 Pierce, Jr.

i 1 Oct. 28, 1975 FLEXIBLE DRAWBACK ASSEMBLY FOR PACKAGE TYING MACHINEPaul Pierce, Jr., La Grange, Ill.

[52] US. Cl. 289/16 [51] Int. Cl. B65H 69/04 [58] Field of Search 289/2,l5, 16; 100/27, 100/33 [56] References Cited UNITED STATES PATENTS216,241 6/1879 Travis 289/16 1,994,453 3/1935 Bunn .1 100/27 2,374,9005/1945 Saxton 289/2 Primary Examiner-Louis K. Rimrodt Attorney, Agent,or FirmMCCaleb, Lucas & Brugman [57] ABSTRACT A flexible drawbackassembly for use in a package tying machine, the assembly beingconnected to the twine wrapper arm of the tying machine for rotationtherewith, and including a connector stem, resilient flexor means, andan extended drawback lever terminating in a string-guide eyelet. Theflexible drawback assembly is resiliently operable and laterallydeflectible to maintain a desired running tension on the twine whilesimultaneously taking up excess slack, and further provides extendedtake-up capabilities since it is relatively unaffected by centrifugalforces, quickly reacts to twine slack variations, and inherently limitsits own range of travel in relation to the wrapper arm.

6 Claims, 3 Drawing Figures a US. Patent Oct. 28, 1975 IWIHI IH FLEXIBLEDRAWBACK ASSEMBLY FOR PACKAGE TYING MACHINE BACKGROUND OF THEINVENTION 1. Field of the Invention This invention relates generally toautomatic tying machines and more particularly to improved drawbackmeans for tensioning the materials used therein.

2. Description of the Prior Art Prior art bundle and package tyingmachines are typically fitted with a drawback assembly to automaticallytension and take up excess slack in the twine as a reach of the twine isbeing wrapped around a bundle. Reference is made to U.S. Pat. Nos.1,606,290, dated Nov. 9, 1926, and 2,898,847, dated Aug. 11, 1959,wherein the operating sequence of a typical package tying machine isdisclosed. Reference is also made to U.S. Pat. Nos. 1,994,453 dated Mar.19, 1935, and 2,371,024, dated Mar. 6, 1945, which disclose a drawbackassembly utilizing a rigid drawback lever, spring anchor bracket, andtension spring means. In the latter patent in particular, the drawbackarm is freely rotatable with the twine wrapper arm and is pivotallymounted on the latters base; the overall range of operating movements inrelation to the machines wrapper arm is limited by angularly extendingfingers.

At the start of a wrapping operation for a typical bundle tying machineas therein described, the initial pull on the twine pulls the drawbacklever into generally parallel alignment with the radial reach of thewrapping arm. As the twine begins to catch up with the wrapper arm,spring biasing forces on the drawback lever return the drawback lever toan acute operating alignment position with respect to the wrapper arm.In this normal operating position, while additional twine is drawn fromthe twine feeder mechanism, the drawback assembly automatically takes upslack within certain inhereint limits. Simultaneously, the drawbackassembly tends to maintain a predetermined running tension on the twineduring wrapping of a bundle.

Because a package tying machine must be able to wrap and tie a reach oftwine around bundles of various sizes, the drawback assembly for thewrapper arm must be capable of proportionally varying amounts of twineslack dependent on package size. Because the drawback levers of priorart drawback assemblies have been of rigid construction, certain take uplimits (both as to speed of take-up and length of take-up) have beeninherently placed on the drawback levers, due on a large part to thetremendous centrifugal forces developed on them during high speedwrapping. Moreover, because the tensioning take-up forces of the priorart drawback assemblies did not directly act on the twine to providedrawback take-up, but rather acted indirectly through a series of leversand pivots, these prior art assemblies were limited in the degrees oftravel through which they operated in relation to the wrapper arm, inthe maximum rotational speeds allowed, and in the speed of recoveryafter initial wrapper arm start up. The above-mentioned indirectdrawback and tensioning further limited the length of drawbackcapability for a specific length drawback lever. Since these variouslimitations in combination limited the range of package sizes capable ofbeing wrapped and tied by a specific size package tying machine, anoperator required several different size machines in order to handle afull range of package sizes. A further problem with the prior artdrawback assemblies centered about the tension spring for the drawbacklever which invariably broke because of repetitive changes in requiredtension.

SUMMARY OF THE INVENTION The present invention overcomes the aforenoteddefects of the prior art and is successfully adaptable to many of thevarious prior art package tying machines. A typical package tyingmachine, like those briefly described above to illustrate the presentinvention, has a rigid twine wrapper arm, rotatably mounted above and tothe rear of the package wrapping table of the tying machine. In order topermit the running speed of the twine to catch up to the almostinstantaneously achieved full rotational speed of the wrapper arm, andfurther, to automatically take up slack in the twine as it is being fedand wrapped about the package by the tying machine, the flexibledrawback assembly of this invention is non-rotatively mounted on thewrapper arm near the latters axis of rotation. Because the flexibledrawback assembly of this invention can simultaneously deflectablychange its own angle of operation in relation to the wrapper arm as wellas exert the necessary take-up force on the twine, it is able to quicklyoperate through an increased travel range. Furthermore, because thedrawback assembly of this invention is of relatively light construction,its effective operating length can be extended without beingdetrimentally affected by centrifugal forces, thereby allowing greaterslack take-up.

The preferred embodiment of the present flexible drawback assemblycomprises a laterally deflectable resilient flexor means in the form ofa coil spring having an extended free ended arm terminating in a loop oreyelet which acts as a guide for the tie material, such as twine. Theother or inner end of the spring is rigidly affixed to the wrapper armof the package tying machine in much the same fashion as prior artdrawback levers, but without any direct limitation on its range ofoperating positions. The anchored, non-pivotal connection of theflexible drawback lever of this invention to a tying machines wrapperarm allows only lateral lever movements, viz, deflections bending thelever laterally of its normal longitudinal axis and made about its fixedend. Such sidewise bending action of the lever of the present inventionis in contradistinction to the freely pivotal movements of the rigidprior art levers, which were limited only by the previously mentionedangularly extending fingers. Because of the relative simplicity of thepreferred embodiment of this invention, the manufacturing costs andoverall number of parts are considerably reduced. Furthermore, due tothe dramatically increased operational ranges of the improved drawbackassembly of this invention, very small packages may be wrapped on alarge tying machine as well as the customary large packages therebypermitting the use of a single size machine for handling a range ofpackage sizes which previously required several different machine sizesaccording to the prior art.

One of the principle objects of this invention is to provide an improveddrawback assembly for use with package tying machines capable of takingup variable amounts of twine slack to thereby expand the range ofpackage size operation for the tying machine.

It is another object of this machine to provide a drawback assembly fora package tying machine of simple,

operationally dependable construction and leading to reducedmanufacturing and maintainance costs.

This invention has as a further object the provision of a drawbackassembly capable of operating directly on the tie materials through anincreased arc of travel.

It is a still further object of this invention to provide a drawbacklever as aforesaid'having a construction that it is only minimallyaffected by centrifugal forces, thereby permitting increased drawbacklever length and resultant greater operating capabilities.

These and other objects, features and advantages of this invention willbecome apparent from the following detailed description of a preferredembodiment thereof illustrated in the accompanying drawings in which:

FIG. 1 is a partial perspective view from the front side of a typicalpackage tying machine embodying this invention;

FIG. 2 is a front fragmentary view of the flexible drawback mechanism ofthis invention and indicating various operating positions therefor; and

FIG. 3 is a fragmentary top view of the flexible drawback of FIG. 2.

' DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1, thereis partially illustrated and generally denoted by reference numeral 11 atypical package tying machine with which this invention is useful. Thetying machine 11 includes a base and support structure (not shown), aplanar package wrapping table 13, and a support bracket 15 which ismounted at the rear of the machine 11 and which extends above the levelof the wrapping table 13. Carried by the support bracket 15 andbearingly supported thereby is a drive shaft 17. Securely connected tothe drive shaft 17, such as by any well-known key and keying means (notshown), is a wrapper arm hub 19 (see FIG. 3) having a drive gear 21formed integrally therewith for rotationally driving the wrapper arm hub19 about the axis of the drive shaft 17. Suitable starter means andmotor driving means (not shown) are located within the base supportstructure of the tying machine 11 and a drive gear chain 23 connects thedriving motor with the drive gear 21. A wrapper arm support 25, in theform of a radial extension of the wrapper arm hub 19 securely carries arigid twine wrapper arm 27 which is of sufficient length that it is ableto wrap a reach of any tie material, such as twine 29, around a bundleor package 31 placed on table 13. Plural string eyelets 33 are mountedon the twine wrapper arm 27 for guiding the twine 29 from a supply (notshown) through a pay out hole 35 to the wrapper arm guide 37.

The preferred form of the flexible drawback assembly of this invention,generally denoted by reference numeral 40 is securely and non-pivotallyfastened to the wrapper arm support 25 by means of a machine bolt 41 asseen in FIGS. 2 and 3. Assembly 40 comprises a connector stem 43 havingan outer end receptive of the bolt 41 for connection to arm hub 19, acoil spring body 45, and an extended drawback lever 47 which terminatesin a string-guide eyelet 49 at its outer end. I

It will be noted that the connector stem 43, the coil spring 45, thedrawback lever 47, and the eyelet 49 are all formed in coaxial alignmentpreferably of a continuous piece of material, such'as suitable springmetal, so as to result in a very simple construction. It further will beunderstood by one skilled in .this art, however, that the flexibledrawback assembly may be formed of multiple pieces suitably interjoined,and alternatively, different laterally deflectible flexor means can besubstituted for coil spring 45.

In order to maintain the assembly in an operational plane generallyparallel to the operational plane of the wrapper arm 27 duringrotational movement thereof, a deflector shield 51 is securely mountedby means of the bolt 41 between the connector stem 43 and the wrapperarm hub 19. The deflector shield 51 may be mounted in a specific angularrelationship to the twine wrapper arm 27, as best seen in FIG. 2, suchthat the spring is given lateral support in one lateral direction forall of its operating positions, as will be explained in greater detailpresently. In this fashion, the effective length-of-drawback of assembly40 is maximized because the same is restrained from swinging side toside in operation. Furthermore,,the deflector shield 51 prohibits theoperating end of flexible assembly 40 i.e., guide eyelet 49, fromfouling the rotational wrapping of the twine 29 by wrapper arm 27.

Turning now to a description of the overall operation of the flexibledrawback assembly of this invention, there are shown in FIG. 2, severalof its operating positions. The position of the drawback lever, shown indashed lines, at 47a which is at the most extreme angle to the twinewrapper arm 27 is its position when the tying machine 11 is at rest andwith a minimally adequate tension in the twine 29. This position is alsoassumed when the knotting operation is being performed on thepackage'31, during which the twine wrapper arm 27 is at rest and theflexible drawback assembly is providing the necessary relaxed tension ontwine 29. Such position also occurs when very small packages are beingwrapped, so that while the twine wrapper arm 27 is under a rotationalwrapping movement, assembly 40 is taking up maximum twine slack.

The laterally deflected position of drawback lever 47 which is shown indashed lines at 47b is one of generally parallel alignment with twinewrapper arm 27. This position for lever 47 occurs when the tying machine1 1 is initially actuated to wrap a reach of twine around the requiringthe twine to move from a zero running speed.

to match the movement of the wrapper arm. Accordingly, to do otherwisebreaks the twine 29. The lever 47 directly and quickly assumes thisgenerally parallel alignment, as illustrated in FIG. 2, because of thelateral deflection capabilities provided by coil spring 45.

When the running speed of the twine (which was originally at rest)catches up to the full rotational wrapping speed of the wrapper arm 27,the assembly 40 quickly reacts and begins to function as a twinetensioning and slack take-up device with the lever 47, moving toward itsnormal operating position as shown in solid lines in FIG. 2. It will beunderstood that during the normal rotational operations of the twinewrapper arm 27 and the following reaction of lever 47, the latter mayassume any of the three positions shown in FIG. 2, as well asinnumerable intermediate positions, depending on the type of tie mediumused, the size of the package 31, the angular and locational placementof package 31 on wrapping table 13, and any other factors whichinfluence the running tension in twine 29.

It can be readily seen that the non-pivotal connection of assembly 40 toarm 27 and the lateral defection capabilities of spring 45 placeinherent limitations on the degree of travel of assembly 40 from oneoperating extreme to the other in relation to wrapper arm 27. Thesefeatures eliminate the need for any angular extending fingers, such asthose disclosed in and required by above referred to U.S. Pat No.2,371,024. Moreover, the flexible drawback assembly hereof more readilyand easily allows for the instant take-up of slack occurring duringtension changes on the twine medium, which feature is most desirablebetween the wrapping and tying cycles. Reference is made to U.S. Pat.No. 3,708,190, for a fuller discussion on the need to provide for suchchanges in the twine tension.

From the foregoing description of the preferred embodiment of thisinvention, it will be obvious to one skilled in the art that variouschanges, modifications and substitutions of equivalents can be made inthe construction of the described flexible drawback assembly for apackage tying machine without departing from the scope of this inventionas defined in the appended claims.

1 claim:

1. In a power-operated package tying machine of the type having arotatably driven wrapper arm for encircling a reach of tie materialabout a package, a flexible drawback apparatus comprising: elongatedflexor means having one end fixed to the machines wrapper arm forrotational movement therewith, said flexor means being operable toresiliently deflect laterally of its longitudinal axis about said fixedend; lever means extending outwardly from the end of said flexor meansopposite said one fixed end; and guide means at the terminal end of saidlever means for slidably coupling the tie material thereto, whereby saidflexible drawback apparatus is operable to resiliently maintain tensionon the tie material throughout operational movements of the wrapper arm.

2. The invention of claim 1, wherein said flexor means comprises a coilspring.

3. The invention of claim 1, wherein said lever means is fixedlyconnected in coaxial alignment with said flexor means.

4. The invention of claim 1, including deflector shield means mountedbetween said flexor means and the wrapper arm for laterally stabilizingsaid flexor means in one lateral direction thereby to maintain saidflexor means and the wrapper arm in parallel operational planes duringrotational movements thereof.

5. A flexible twine drawback assembly for a bundle tying machine,comprising: twine means rotatably wrapped about a bundle by thepower-driven wrapper arm of a bundle tying machine; coil spring meanshaving one end securely anchored to said rotatable, powerdriven twinewrapper arm, said coil spring means having the other end thereof formedto provide an elongated twine drawback lever, a twine guide formed atthe terminal end of said lever for coupling said twine means thereto,said coil spring means being operable to deflect laterally about itsanchored end thereby causing said extended lever and twine guide tomaintain tension in said retained twine means and reactively take upslack variations occurring therein.

6. In a package tying machine, the combination comprising: a packagewrapping table having support means; twine means, a rotatably driventwine-wrapping arm means for wrapping a reach of said twine means abouta package on said table; and flexible twine drawback means having oneend non-rotatively fixed to said twine-wrapping arm means to rotatetherewith and having the other end thereof operable to translatelaterally relative to said wrapper arm means to maintain tension on saidtwine means; said drawback means comprising interjoined laterallydeflectible resilient flexor means, extended lever means, and guidemeans on said lever means for slidably coupling said twine meansthereto.

1. In a power-operated package tying machine of the type having a rotatably driven wrapper arm for encircling a reach of tie material about a package, a flexible drawback apparatus comprising: elongated flexor means having one end fixed to the machine''s wrapper arm for rotational movement therewith, said flexor means being operable to resiliently deflect laterally of its longitudinal axis about said fixed end; lever means extending outwardly from the end of said flexor means opposite said one fixed end; and guide means at the terminal end of said lever means for slidably coupling the tie material thereto, whereby said flexible drawback apparatus is operable to resiliently maintain tension on the tie material throughout operational movements of the wrapper arm.
 2. The invention of claim 1, wherein said flexor means comprises a coil spring.
 3. The invention of claim 1, wherein said lever means is fixedly connected in coaxial alignment with said flexor means.
 4. The invention of claim 1, including deflector shield means mounted between said flexor means and the wrapper arm for laterally stabilizing said flexor means in one lateral direction thereby to maintain said flexor means and the wrapper arm in parallel operational planes during rotational movements thereof.
 5. A flexible twine drawback assembly for a bundle tying machine, comprising: twine means rotatably wrapped about a bundle by the power-driven wrapper arm of a bundle tying machine; coil spring means having one end securely anchored to said rotatable, power-driven twine wrapper arm, said coil spring means having the other end thereof formed to provide an elongated twine drawback lever, a twine guide formed at the terminal end of said lever for coupling said twine means thereto, said coil spring means being operable to deflect laterally about its anchored end thereby causing said extended lever and twine guide to maintain tension in said retained twine means and reactively take up slack variations occurring therein.
 6. In a package tying machine, the combination comprising: a package wrapping table having support means; twine means, a rotatably driven twine-wrapping arm means for wrapping a reach of said twine means about a package on said table; and flexible twine drawback means having one end non-rotatively fixed to said twine-wrapping arm means to rotate therewith and having the other end thereof operable to translate laterally relative to said wrapper arm means to maintain tension on said twine means; said drawback means comprising interjoined laterally deflectible resilient flexor means, extended lever means, and guide means on said lever means for slidably coupling said twine means thereto. 